Forming fabric with machine side layer weft binder yarns

ABSTRACT

A flat woven papermaker&#39;s forming fabric having a paper side layer and a machine side layer interconnected by pairs of machine side layer weft binder yarns. Each of the binder yarn pair members in sequence interlaces with a portion of the machine side layer warp yarns in segments of the weft yarn path so as to complete an unbroken weft path in the machine side layer weave pattern, and to provide an internal machine side layer float. Each of the binder yarn pair floats interweaves with a paper side layer warp yarn so as to bind the paper and machine side layers together. The location of the internal floats in each layer determines the available interweaving locations, not all of which need be used. A wider choice of possible paper and machine side layer weave design combinations is thus made available in forming fabrics, thereby allowing for a better match between the forming fabric and the paper maker&#39;s requirements.

FIELD OF THE INVENTION

The present invention relates to flat woven papermaker's forming fabricshaving a paper side layer and a machine side layer interconnected bymachine side layer weft binder yarn pairs. Within the overall fabricweave pattern, the number of machine side layer weft yarns between eachpair of weft binder yarns can zero, one, two or three.

BACKGROUND OF THE INVENTION.

Flat woven papermaker's forming fabrics in which paper side layer weftbinder yarn pairs are used to interconnect the weave structures of thepaper and machine side layers are well known. Various arrangements havebeen described, for example by Wilson, U.S. Pat. No. 5,518,042;Vohringer, U.S. Pat. No. 5,152,326; Quigley et al., U.S. Pat. No.5,520,225; Ostermayer et al., U.S. Pat. No. 5,542,455; Wright, U.S. Pat.No. 5,564,475; Wilson, U.S. Pat. No. 5,641,001; Ward, U.S. Pat. No.5,709,250; Seabrook et al., U.S. Pat. No. 5,826,627; and Wilson, U.S.Pat. No. 5,937,914. Many others are known. None of these referencesdiscuss in any detail the impact of the use of weft binder pairs on theproperties of the machine side layer.

As used herein, the following terms have the following meanings.

The term “weft binder yarn” refers to each yarn of a pair of yarns whichtogether occupy a single unbroken weft path in the machine side layer,and which separately interweave with a paper side layer warp yarn.

The term “interweave” refers to a locus at which a yarn forms at leastone knuckle with another yarn in the paper side layer.

The term “interlace” refers to a locus at which a yarn forms at leastone knuckle with another yarn in the machine side layer.

The term “segment” refers to a locus at which a weft binder yarninterlaces with at least one machine side layer warp within the machineside layer.

The term “float” refers to that portion of a yarn which passes over, orunder, a group of other yarns in the same layer of the fabric withoutinterweaving or interlacing with them. The associated term “floatlength” refers to the length of a float, expressed as a numberindicating the number of yarns passed over, or under, as appropriate. Afloat can be exposed on the machine side or paper side of each of thepaper side layer and the machine side layer. The term “internal float”thus refers to a float exposed between the two layers, either on themachine side of the paper side layer, or on the paper side of themachine side layer.

The terms “symmetry” and “asymmetry”, and the associated terms“symmetrical” and “asymmetrical”, refer to the shape of the pathoccupied by a weft binder yarn as it exits the machine side layer,interweaves with a paper side layer warp, and enters the machine sidelayer. The path is symmetrical when the interweaving point is locatedsubstantially at the middle of the path, and the number of warp yarnsbetween the exit point and the interweaving point is equal to, or nearlyequal to, the number of yarns between the interweaving point and theentry point.

The notation such as 3/2 in reference to a fabric design refers to thenumber of warp, or machine direction yarns, over or under which a weft,or cross machine direction yarn, floats within the weave pattern. Thus3/2 means that a weft yarn floats over three warp yarns and then undertwo warp yarns within the weave pattern.

The prior art, as exemplified above, seems to have limited the designsof forming fabrics of this type to those in which weft binder yarn pairsare used to provide an intrinsic component of the paper side layer weavedesign, and to enhance the paper side layer formation characteristics,as in the Wilson and Seabrook patents. The prior art designs alsocreated limitations which were generally believed to be necessary tomaximise fabric stability, reduce or even eliminate sleaziness (themovement of one of the two layers relative to the other) and fabricdelamination (the catastrophic separation of the two layers caused byboth internal and external abrasion of the weft binder yarns). The priorart generally served to restrict the number of paper side layer andmachine side layer weave designs that could be combined together. It isthus apparent that a great deal of experimental effort had to beexpended in order to find compatible combinations of paper and machineside layer weave designs capable of interconnection by means of weftbinder yarns, due to the restrictive criteria noted above.

BRIEF SUMMARY OF THE INVENTION

This invention is based on the discovery that machine side layer weftyarns can be successfully used as weft binder yarn pairs in fabrics ofthis type. The machine side layer weft binder yarn paths can also bechosen to minimise internal stresses introduced during weaving the twolayer fabric. Further, their use also appears to provide significantlygreater flexibility in the choice of compatible paper side layer andmachine side layer weave designs. In this invention, within the weavepattern repeat, there is either zero, one, two or three machine sidelayer weft yarns between each pair of machine side layer weft binderyarns. It is thus possible to match the locations of the internal floatsof the weft binder yarns within the machine side layer pattern repeat tothe desired paper side layer interweaving locations, so that they arelocated more or less at the midpoints of the paper side layer internalwarp floats. The paper side layer weave design is selected so as to beappropriate for the paper product to be made using the forming fabric.It is also now possible to select the machine side layer weave design tooptimise machine side layer properties, and then to select interweavingpoints that are located more or less at the midpoints of the internalfloats of the weft binder yarns. It has also been discovered that notall of the available interweaving locations have to be used: it ispossible to leave some of them out within the forming fabric weavepattern repeat.

In the fabrics of this invention, the paper side layer internal warpfloat should be as long as possible, with the interweaving point locatedas close as possible to the middle of this float. The path occupied bythe machine side layer weft binder yarn internal float should be assymmetrical as possible about the interweaving point. Further, in thefabrics according to this invention all of the machine side layer weftyarns are substantially the same size, and therefore although at leastsome, if not all, are doubled as weft binder yarn pairs, all of themcontribute to the properties of the machine side layer of the fabric.The paper side layer weft yarns will frequently be smaller than themachine side layer weft yarns, and may also be larger.

The interweaving locations of the paper side layer and machine sidelayer floats should be chosen with some care. The limitation on both ofthese floats appears to be that each should be as long as is reasonablypossible. In its path in between the two layers, the machine side layerweft float has essentially a “V” shape: as the float length increases,the V is flattened reducing the out of plane stresses. If the V shapedpath is not symmetrical, or the float is relatively short, any stressesimposed on the forming fabric are increased at the shorter end of thefloat. The upper limits on these two float lengths cannot be directlydetermined.

STATEMENT OF THE INVENTION

The present invention seeks to provide a papermaker's forming fabriccomprising in combination a paper side layer including a first set ofwarp and weft yarns interwoven according to a first pattern whichprovides for internal floats of the paper side layer warp yarns, amachine side layer including a second set of warp and weft yarns, inwhich the weft yarns include weft binder yarn pairs, interwovenaccording to a second pattern which provides for internal floats of themachine side layer weft binder yarns, wherein within the fabric weavepattern repeat:

(i) the weft binder yarn pairs together occupy successive segments of anunbroken weft path within the machine side layer;

(ii) at least some of the machine side layer weft binder yarn internalfloats interweave with paper side layer internal warp yarn floats;

(iii) there is zero, one, two or three machine side layer weft yarnsbetween each pair of binder yarns; and

(iv) the paper side layer warp yarn internal float length is at least 2.

Preferably, within the weave pattern repeat, the number of machine sidelayer weft yarns between each pair of weft binder yarns is constant.Alternatively, within the weave pattern repeat, the number of machineside layer weft yarns between each pair of weft binder yarns is notconstant.

Preferably, the segments of the weft binder yarn unbroken weft pathoccupied by each member in succession are the same length.Alternatively, the segments of the weft binder yarn unbroken weft pathoccupied by each member in succession are not the same length.

Preferably, each member of a weft binder yarn pair interweaves at ornear to the midpoint of an internal paper side layer warp yarn float.

Preferably, within the pattern repeat, the majority of the paper sidelayer warp yarns interweave once with a machine side layer weft binderyarn.

Preferably, the path occupied by each weft binder yarn, as it passesfrom interlacing with the machine side layer warp yarns in a segment ofthe machine side layer weft yarn path to interweave with a paper sidelayer warp yarn internal float and returns to interlace with the machineside layer warp yarns in another segment of the machine side layer weftyarn path, is more or less symmetrical about the interweaving point.

Preferably, the paper side layer warp yarn internal float length is atleast three. Most preferably, the paper side layer warp yarn internalfloat length is four or more.

Preferably, the paper side layer is woven according to a weave designchosen from the group consisting of: a 2/1 twill, a 2/1 broken twill, a2/1 satin, a 2/2 basket weave, a 2/2 twill, a 3/1 twill, a 3/1 brokentwill, a 3/1 satin, a 3/2 twill, a 3/2 satin, a 4/1 twill, a 4/1 brokentwill, a 4/1 satin, a 5/1 twill, a 5/1 broken twill, and a 5/1 satin.

Preferably, the machine side layer is woven to a weave design chosenfrom the group consisting of: a plain weave, a 2/1 twill, a 2/1 brokentwill, a 2/1 satin, a 2/2 basket weave, a 3/1 twill, a 3/1 broken twill,a 3/1 satin, a 3/2 twill, a 3/2 satin, a 4/1 twill, a 4/1 broken twill,a 4/1 satin, a 5/1 twill, a 5/1 broken twill, a 5/1 satin, a 6/1/ twill,a 6/1 broken twill, a 6/1 satin, and an N×2N design as disclosed byBarrett in U.S. Pat. No. 5,544,678.

Preferably, the ratio of the number of paper side layer weft yarns tothe number of machine side layer weft yarns is chosen from the groupconsisting of: 1:1, 3:2, 5:3, 2:1 or 3:1, when the weft binder yarns areincluded, and a pair of weft binder yarns counted as one machine sidelayer weft yarn.

Preferably, the ratio of the number of paper side layer warp yarns tothe number of machine side layer warp yarns is 1:1. Alternatively, theratio of the number of paper side layer warps to the number of machineside layer warps is 2:1.

Both the paper side layer and the machine side layer may be wovenaccording any known weave design which would be acceptable for theintended use of the fabric, with the proviso that the paper side layermust be woven according to a design which provides for an internal warpfloat length of at least 2, and desirably it is at least 3 or more,since it is then possible to find more acceptable interweaving locationsfor the weft binder yarns.

Preferably, the fabrics of this invention have a 5/1 broken twill paperside layer weave which provides for a paper side layer warp internalfloat length of five yarns, and a 2/1 twill machine side layer design.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a weft profile for a first fabric according to this invention;

FIG. 2 is a warp profile for the fabric of FIG. 1;

FIG. 3 is a weave diagram for the fabric of FIG. 1;

FIG. 4 is a weft profile for a second fabric according to thisinvention;

FIG. 5 is a warp profile for the fabric of FIG. 4;

FIG. 6 is a weave diagram for the fabric of FIG. 4;

FIG. 7 is a weft profile for a third fabric according to this invention;

FIG. 8 is a warp profile for the fabric of FIG. 7;

FIG. 9 is a weave diagram for the fabric of FIG. 7;

FIG. 10 is a weft profile for a fourth fabric according to thisinvention;

FIG. 11 is a warp profile for the fabric of FIG. 10;

FIG. 12 is a weave diagram for the fabric of FIG. 10;

FIG. 13 is a weft profile for a fifth fabric according to thisinvention;

FIG. 14 is a warp profile for the fabric of FIG. 13;

FIG. 15 is a weave diagram for the fabric of FIG. 13;

FIG. 16 is a weft profile for a sixth fabric according to thisinvention;

FIG. 17 is a warp profile for the fabric of FIG. 16;

FIG. 18 is a weave diagram for the fabric of FIG. 16;

FIG. 19 is a weft profile for a seventh fabric according to thisinvention;

FIG. 20 is a warp profile for the fabric of FIG. 19;

FIG. 21 is a weave diagram for the fabric of FIG. 19;

FIG. 22 is a weft profile for an eighth fabric according to thisinvention;

FIG. 23 is a warp profile for the fabric of FIG. 22; and

FIG. 24 is a weave diagram for the fabric of FIG. 22.

In all of the weft and warp profiles the paper side surface of theforming fabric is at the top, the machine side surface is at the bottom,and the cut yarns are shown as shaded circles. In the weft profiles, thepaper side layer weft is shown dotted, and the machine side layer weftbinder yarn pair as one solid and the other chain-dotted. In the warpprofiles, the paper side layer warp is shown solid, and the machine sidelayer warp is shown dotted.

The same numbers are used for the warps and wefts within each set ofthree related figures. Paper side layer warp yarns are numbered from 10to 29, machine side layer warp yarns from 30 to 49, paper side layerweft yarns are numbered from 50 to 69, and machine side layer weft yarnsfrom 70 to 89, in each case as required.

In determining warp yarn ratios between each of the layers, every warpis counted for each layer. In determining weft yarn ratios, everymachine side layer weft binder yarn pair is counted as one weft. Theratio is always given as paper side layer:machine side layer.

In the weave diagrams, the left section is the paper side layer design,and the right section is the machine side layer design. The warps foreach layer are numbered from left to right in two sets. The weft forboth layers are numbered down the left side only; each member of amachine side layer weft binder yarn pair is given a separate number (i.ein FIG. 3 weft 70 and 71 are the two members of a pair). In the wovenfabric the paper side layer weft will be physically located more or lessabove the machine side layer weft. A filled in square indicates where aweft passes under a warp within that layer. A circle in both sectionsindicates a location at which one member of a machine side layer weftbinder yarn pair interweaves with a paper side layer warp yarn.

The eight fabrics shown in the Figures will now be discussed in turn.

The fabric in FIGS. 1, 2 and 3 is woven in 20 sheds, using 10 sheds foreach of the layers. The paper side layer is a 4/1 broken twill, and themachine side layer is also a 4/1 broken twill. All of the machine sidelayer weft are used in pairs as weft binder yarns; there are no other“ordinary” machine side layer weft yarns. The warp ratio is 1:1, and theweft ratio is 2:1.

Inspection of FIGS. 1 and 3 shows that the machine side layer brokentwill weave used provides a long internal weft binder yarn float, andthat the interweaving point is as near to the middle of the binder weftyarn float as possible: for example, weft 70 floats over warps 34-39,and interweaves with warp 16 above warp 36. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 2 and 3shows that the broken twill weave used provides a lengthy exposedinternal paper side layer warp float, and that the interweaving point isclose to the midpoint of this float: warp 10 floats under wefts 53-58,and interweaves with weft 76 adjacent to weft 56.

The fabric in FIGS. 4, 5 and 6 is woven in 20 sheds, using 10 sheds foreach of the layers. The paper side layer is a 4/1 broken twill, and themachine side layer is a 3/2 twill. All of the machine side layer weftare used in pairs as weft binder yarns; there are no other “ordinary”machine side layer weft yarns. The warp ratio is 1:1, and the weft ratiois 2:1.

Inspection of FIGS. 4 and 6 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point 15 as near to the middle of the binder weft yarnfloat as possible: for example, weft 70 floats over warps 33-39, andinterweaves with warp 16 above warp 36. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 5 and 6shows that the broken twill weave used provides a lengthy exposedinternal paper side layer warp float, and that the interweaving point isclose to the midpoint of this float: warp 10 floats under wefts 53-58,and interweaves with weft 76 adjacent to weft 56.

The fabric in FIGS. 7, 8 and 9 is woven in 24 sheds, using 12 sheds foreach of the layers. The paper side layer is a 5/1 broken twill, and themachine side layer is a 4/2 twill. All of the machine side layer weftare used in pairs as weft binder yarns; there are no other “ordinary”machine side layer weft yarns. The warp ratio is 1:1, and the weft ratiois 2:1.

Inspection of FIGS. 7 and 9 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point is as near to the middle of the binder weft yarnfloat as possible: for example, weft 70 floats over warps 31-37, andinterweaves with warp 14 above warp 34. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 8 and 9shows that the broken twill weave used provides a lengthy exposedinternal paper side layer warp float, and that the interweaving point isclose to the midpoint of this float: warp 10 floats under wefts 51-55,and interweaves with weft 72 adjacent to weft 53.

The fabric in FIGS. 10, 11 and 12 is woven in 20 sheds, using 10 shedsfor each of the layers. The paper side layer is a 4/1 twill, and themachine side layer is a 3/2 twill. Not all of the machine side layerweft are used in pairs as weft binder yarns; there is one non-bindingweft(machine side layer wefts 72, 75, 78, 81, and 84) between each pairof weft binder yarns. The warp ratio is 1:1, and the weft ratio is 2:1.

Inspection of FIGS. 10 and 12 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point is as near to the middle of the binder weft yarnfloat as possible: for example, weft 71 floats over warps 32-30, andinterweaves with warp 15 above warp 35. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 11 and 12shows that the twill weave used provides an exposed internal paper sidelayer warp float, and that the interweaving point is close to themidpoint of this float: warp 10 floats under wefts 69, 50, 51 and 52,and interweaves with weft 72 between wefts 50, 51.

The fabric in FIGS. 13, 14 and 15 is woven in 24 sheds, using 12 shedsfor each of the layers. The paper side layer is a 5/1 twill, and themachine side layer is a 4/2 broken twill. All of the machine side layerweft are used in pairs as weft binder yarns; there are no other“ordinary” machine side layer weft yarns. The warp ratio is 1:1, and theweft ratio is 2:1.

Inspection of FIGS. 13 and 15 shows that the machine side layer brokentwill weave used provides a long internal weft binder yarn float, andthat the interweaving point is as near to the middle of the binder weftyarn float as possible: for example, weft 70 floats over warps 31-38,and interweaves with warp 14 above warp 34. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 14 and 15shows that the twill weave used provides a lengthy exposed internalpaper side layer warp float, and that the interweaving point is close tothe midpoint of this float: warp 10 floats under wefts 51-55, andinterweaves with weft 72 adjacent to weft 53.

The fabric in FIGS. 16, 17 and 18 is woven in 24 sheds, using 12 shedsfor each of the layers. The paper side layer is a 5/1 broken twill, andthe machine side layer is a 4/2 broken twill. All of the machine sidelayer weft are used in pairs as weft binder yarns; there are no other“ordinary” machine side layer weft yarns. The warp ratio is 1:1, and theweft ratio is 2:1.

Inspection of FIGS. 16 and 18 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point is as near to the middle of the binder weft yarnfloat as possible: for example, weft 70 floats over warps 41 and 30-36,and interweaves with warp 13 above warp 33. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 17 and 18shows that the broken twill weave used provides a lengthy exposedinternal paper side layer warp float, and that the interweaving point isclose to the midpoint of this float: warp 10 floats under wefts 51-55,and interweaves with weft 72 adjacent to weft 53.

The fabric in FIGS. 19, 20 and 21 is woven in 24 sheds, using 12 shedsfor each of the layers. The paper side layer is a 5/1 twill, and themachine side layer is a 3/3 broken twill. All of the machine side layerweft are used in pairs as weft binder yarns; there are no other“ordinary” machine side layer weft yarns. The warp ratio is 1:1, and theweft ratio is 2:1.

Inspection of FIGS. 19 and 21 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point is as near to the middle of the binder weft yarnfloat as possible: for example, weft 74 floats over warps 31-39, andinterweaves with warp 15 above warp 35. It also shows that the pathsoccupied by the two members of each weft binder pair are the same, andthus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 20 and 21shows that the twill weave used provides a lengthy exposed internalpaper side layer warp float, and that the interweaving point is close tothe midpoint of this float: warp 10 floats under wefts 51-55, andinterweaves with weft 72 adjacent to weft 53.

The fabric in FIGS. 22, 23 and 24 is woven in 20 sheds, using 10 shedsfor each of the layers. The paper side layer is a 4/1 broken twill, andthe machine side layer is a 3/2 twill. All of the machine side layerweft are used in pairs as weft binder yarns; there are no other“ordinary” machine side layer weft yarns. The warp ratio is 1:1, and theweft ratio is 2:1.

Inspection of FIGS. 22 and 24 shows that the machine side layer twillweave used provides a long internal weft binder yarn float, and that theinterweaving point is as near to the middle of the binder weft yarnfloat as possible: for example, weft 71 floats over warps 32-38, andinterweaves above with warp 15 above warp 35. It also shows that thepaths occupied by the two members of each weft binder pair are the same,and thus the segment lengths occupied by each member of the pair in themachine side layer weft path are equal. Inspection of FIGS. 23 and 24shows that the broken twill weave used provides an exposed internalpaper side layer warp float, and that the interweaving point is close tothe midpoint of this float: warp 10 floats under wefts 59 and 50-52, andinterweaves with weft 70 between wefts 51, 52.

It is noted above that in the prior art fabrics using paper side layerweft binder yarns all of the available interlacing points between eachweft binder yarn pair member and a machine side layer warp are utilised.In the fabrics of this invention, it has been found that it is notnecessary that all of the available interweaving locations between themachine side layer weft binder yarns and the paper side layer warp yarninternal floats be utilized. Some interweaving points can be omitted inalternating repeats of the weave designs chosen for the paper side layerand the machine side layer. Although the weave designs chosen for eachof the two layers are not affected by such an omission, and thus appearto continue unchanged, such an alternating omission has the effect ofdoubling the machine direction length of the weave pattern repeat forthe forming fabric.

The warp and weft yarns used in the forming fabrics of this inventionwill generally be thermoplastic monofilaments. Both the cross sectionalshape, filament dimensions, warp fill, weft fill, and paper side surfaceopen area will be chosen to provide the properties required in thefabric. Fabrics according to this invention have been found to beparticularly suitable for tissue grades of paper products.

The forming fabrics of this invention show improved machine side layerproperties, for example improved machine side layer resistance to wear,and improved forming fabric properties, for example cross-machinedirection stiffness and overall stability. Fabric stiffness andstability are related to the number of interweaving locations, and bothincrease as the number of locations increases. Improved cross machinestiffness is of relevance when the fabric is subjected to relativelyhigh tension on the forming section, since a stiffer fabric resistsnarrowing better. The forming fabrics of this invention also permit theuse of relatively longer paper side layer weft floats without undulydetracting from fabric stiffness or stability.

The long paper side layer floats also provide improved cross-machinedirection support for paper making fibres orientated in the machinedirection, without hindering drainage of the incipient paper product webthrough the forming fabric. This is useful in the manufacture of somegrades of product, such as tissue and packaging, where some wire mark inthe products is acceptable, and is in fact beneficial in some productsas it increases sheet bulk. The 5/1 broken twill paper side layer weavedesign combined with a 2/1 twill machine side layer has been found to beparticularly useful, due to its wear resistance.

What is claimed is:
 1. A papermaker's forming fabric comprising incombination a paper side layer including a first set of warp and weftyarns interwoven according to a first pattern which provides forinternal floats of the paper side layer warp yarns, a machine side layerincluding a second set of warp and weft yarns, in which the weft yarnsinclude weft binder yarn pairs, interwoven according to a second patternwhich provides for internal floats of the machine side layer weft binderyarns, wherein within the fabric weave pattern repeat: (i) the weftbinder yarn pairs together occupy successive segments of an unbrokenweft path within the machine side layer; (ii) at least some of themachine side layer weft binder yarn internal floats interweave withpaper side layer internal warp yarn floats; (iii) there is zero, one,two or three machine side layer weft yarns between each pair of binderyarns; and (iv) the paper side layer warp yarn internal float length isat least
 2. 2. A fabric according to claim 1 wherein the segments of theweft binder yarn unbroken weft path occupied by each member insuccession are the same length.
 3. A fabric according to claim 1 whereinthe segments of the weft binder yarn unbroken weft path occupied by eachmember in succession are not the same length.
 4. A forming fabricaccording to claim 1 wherein each weft binder yarn interlaces at or nearto the midpoint of an internal paper side layer warp yarn float.
 5. Aforming fabric according to claim 1 wherein within the pattern repeat,each machine side layer weft binder yarn interweaves at least once witha paper side layer warp yarn.
 6. A forming fabric according to claim 1wherein the path occupied by each weft binder yarn, as it passes frominterlacing with the machine side layer warp yarns in a segment of themachine side layer weft yarn path to interweave with a paper side layerwarp yarn internal float and returns to interlace with the machine sidelayer warp yarns in another segment of the machine side layer weft yarnpath, is more or less symmetrical about the interweaving point.
 7. Aforming fabric according to claim 1 wherein the paper side layer warpyarn internal float length is at least three.
 8. A forming fabricaccording to claim 1 wherein the paper side layer warp yarn float lengthis at least four.
 9. A forming fabric according to claim 1 wherein thepaper side layer is woven according to a weave design chosen from thegroup consisting of: a 2/1 twill, a 2/1 broken twill, a 2/1 satin, a 2/2basket weave, a 2/2 twill, a 3/1 twill, a 3/1 broken twill, a 3/1 satin,a 3/2 twill, a 3/2 satin, a 4/1 twill, a 4/1 broken twill, a 4/1 satin,a 5/1 twill, a 5/1 broken twill, and a 5/1 satin.
 10. A forming fabricaccording to claim 1 wherein the machine side layer is woven accordingto a weave design chosen from the group consisting of: a plain weave, a2/1 twill, a 2/1 broken twill, a 2/1 satin, a 2/2 basket weave, a 3/1twill, a 3/1 broken twill, a 3/1 satin, a 3/2 twill, a 3/2 satin, a 4/1twill, a 4/1 broken twill, a 4/1 satin, a 5/1 twill, a 5/1 broken twill,a 5/1 satin, a 6/1/ twill, a 6/1 broken twill, a 6/1 satin, and an N×2Ndesign as disclosed by Barrett in U.S. Pat. No. 5,544,678.
 11. A formingfabric according to claim 1 wherein the ratio of the number of paperside layer weft yarns to the number of machine side layer weft yarns ischosen from the group consisting of: 1:1, 3:2, 5:3, 2:1 or 3:1, when theweft binder yarns are included, and a pair of weft binder yarns countedas one paper side layer weft yarn.
 12. A forming fabric according toclaim 1 wherein in the machine side layer weave repeat pattern two pairsof weft binder yarns are separated by zero machine side layer weft yarn.13. A forming fabric according to claim 1 wherein in the machine sidelayer weave repeat pattern two pairs of binder yarns are separated byone machine side layer weft yarns.
 14. A forming fabric according toclaim 1 wherein at at least one locus within the forming fabric patternrepeat a weft binder yarn internal exposed float is not interwoven witha paper side layer warp.